Field of the Invention
The present invention relates to a planetary gear set, and more particularly, to a rotation support structure of a planetary gear set for a power transmission system that supports rotation of the planetary gear set applied to the power transmission system of a vehicle.
Description of Related Art
An environmentally-friendly technology of a vehicle is a core technology which controls a survival of a future automobile industry and advanced car makers have focused their own energy on the development of an environmentally-friendly vehicle to achieve environment and fuel efficiency regulations.
Therefore, each car maker has developed an electric vehicle (EV), a hybrid electric vehicle (HEV), a fuel cell electric vehicle (FCEV), and the like, as a future vehicle technology.
As described above, since a future vehicle has several technical restrictions such as weight, cost, and the like, the car makers have paid attention to a power transmission system as an alternative to solve realistic problems such satisfaction of exhaust gas regulations and enhancement of fuel efficiency performance and are fiercely competing to commercialize the power transmission system.
Thus, in order to improve fuel efficiency performance, the power transmission system applied to the vehicle includes at least one planetary gear set so that the power transmission system has a plurality of gear shift stages.
The planetary gear set has a sun gear, a planet carrier, and a ring gear that are a rotation element. The rotation element is supported by a transmission housing or a front housing. A plurality of bearings are required to support the rotation element.
The power transmission system including multi-stage transmission over 8 stages (e.g., an eighth speed) was developed recently so that the number of the planetary gear set was increased. Therefore, there are lots of constraints when a rotation support structure for the planetary gear set is designed within the transmission housing that has a narrow space.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.